1. Field of the Invention
The present invention relates to effect devices and, in particular to effect devices by which feedback performance can be carried out easily.
2. Description of the Related Art
A performance technique for the electric guitar, which is one of the stringed instruments, involves the use of feedback. In the feedback performance, the player plucks the strings of the electric guitar and moves the electric guitar, while the strings are still vibrating, close to a loudspeaker of a guitar amplifier that is amplifying musical tones based on the plucking of the strings and emanating sounds. By performing this operation, a feedback loop is formed from the strings of the electric guitar, the loudspeaker and the acoustic space between the loudspeaker and the electric guitar. In this feedback loop, the strings being plucked are further vibrated by resonance caused by the musical tones (musical tones based on plucking of the strings) emanated from the loudspeaker, whereby the feedback performance is realized.
However, the feedback performance is a performance technique that requires subtle control in, for example, the manner in which the strings are plucked, the distance between the loudspeaker and the strings, the direction and timing in which the strings are moved closer to the loudspeaker, the sound volume (output level) of musical tone emanated from the loudspeaker and the like. Thus, feedback performance provides a high degree of difficulty for musicians, which means that performers often fail in successfully executing feedback performance.
Japanese Utility Model Patent Application HEI 6-25898 describes an effect device that detects the pitch of musical tone pronounced by plucking the strings, and sets a band-pass filter to pass only frequency components in a predetermined passband width in which the frequency corresponding to the detected pitch is assumed to be a center frequency. This effect device allows the musical tone with a desired pitch to be produced by plucking the strings (that is, in the electric guitar, the musical tone with a pitch that is specified by the performer by pressing the strings against the fret, and may be referred to as the “fundamental (fundamental tone)” or the “keynote”) such that the frequency component of the musical tone is emphasized in the output and, as a result, the vibration of the strings can be continued with the frequency of the fundamental.